Simply extending the mast and thereby raising the top of the umbrella, where the ribs are connected, would not solve the problem. This would thus lead to a correspondingly higher position of the slider in the unfolded position of the umbrella, so that the umbrella could not be handled by persons with normal or even shorter length.
Another problem of large free standing umbrellas is that the bigger size of the canopy automatically leads to a higher weight of the ribs and/or the canopy. The unfolding and folding of the umbrella therefore becomes more difficult.
The U.S. Pat. No. 4,424,824 A discloses an umbrella having a support tube uppermost end portion into which is telescopically received an umbrella shaft carrying a crown to which is pivotally connected cover ribs, a sleeve in external telescopic relationship to the support tube, a plurality of struts pivotally connected between the sleeve and the cover ribs, a threaded spindle within the umbrella shaft threaded relative to a threaded nut fixed to the umbrella shaft, and a flexible element, such as a cable, rope or wire, having ends fixed to the sleeve and to the umbrella shaft and being guided over a pulley carried by the umbrella shaft. As a result, the procedure of opening and closing the umbrella canopy is very complex. The umbrella canopy is closed, while the umbrella shaft is extended, in others words, closing or opening the umbrella canopy and extending or retracting the umbrella shaft are working at the same time, namely the two actions are synchronous. The length of the guide tube extended outward from the support tube is very long, so the top of the closed umbrella will be very high. This is disadvantageous e.g. when storing the umbrella away, in particular under a roof or such. Also the known umbrella needs more space when closed for transport, which i.a. leads to higher costs for shipping. Additionally, in order to facilitate the opening and closing procedure, the overall operating-system of the known umbrella includes threaded means in the form of a threaded spindle supported in an undisplaceable or fixed fashion at a lower end portion by means of gear means in the form of a miter gear. This makes the fabrication of the known umbrella complicated, time consuming and costly. A more simple system for facilitating the folding and unfolding of an umbrella is known from the U.S. Pat. No. 8,087,420 B1, which discloses an umbrella system which includes a counterweight and system of pulleys, where the system of pulleys includes class 1 and class 2 pulleys configured with the counterweight to gain a mechanical advantage in the normal operation of the umbrella. This prior art, however, does not teach any solution or even discusses the problem of the long ribs at large canopies.